BandidoIIuMax PCB

[Peter Morf]

Hi all!
I designed a PCB for BandidoIIuMax, but I havn't constructed it yet.
It may be a good idea to show it here to you all in case there are any errors.
What du you think of this?

[Peter Morf]

Sorry I messed up the placement image, here's the correct one:

[exciter]

Hi,
nice PCB
Shouldnt D3 cathode directly connected to IC1-Pin11???

[Peter Morf]

You'r right.. I have messed up som of the parts. I see that D1-D3 actually is D8-D10

Thanks!

[exciter]

Will check also against schematic.
im looking forward to build another detector with disc. so this may be a good project.
regards

[Peter Morf]

It's been a while since I designed this PCB (2005), I just found it and wanted to give it a chance. I used Carls schematic (http://geotech.thunting.com/pages/me...didoIIuMax.pdf) so the diodes 1-3 are the ones connected to IC1 (4024).

[Max]

Hi all!
I designed a PCB for BandidoIIuMax, but I havn't constructed it yet.
It may be a good idea to show it here to you all in case there are any errors.
What du you think of this?

Hi Peter,
seems really good work. I don't know if all is right in that PCB but it looks great. Small...with a large gnd plane and not too small cause sometimes you have to deal with oversmaller pcbs...that don't let you put all those components on them. Yours seems ok from my prospective. A good compromise between dimensions and components placing.

I've realized bandidoII clone on Gary's 1st design and it is good working now that I've shielded it in a good metal box...but I really like gnd planes on this kind of circuits cause there could be many falsing due to noise and crosstalks in larger boards. Also you can test them easy without external shielding if good gnd plane is present...

I haven't much time at now...but, if I can, I'll check your board too for errors and report here on the forum.

Thanks,
Max

[Peter Morf]

One more

I found another PCB I made some time ago. Its 10.0 X 8.0 cm.
This one has two options: the salt-mode and you can add an extra battery just for powering sound (If it may help to make it more stable?)
So.. now I don't know which one to choose =)

[Peter Morf]

And the schematic

[Max]

I found another PCB I made some time ago. Its 10.0 X 8.0 cm.
This one has two options: the salt-mode and you can add an extra battery just for powering sound (If it may help to make it more stable?)
So.. now I don't know which one to choose =)

Hi Peter,
don't know if it's useful having salt-mode on bandido...cause you loose disc on most iron...and so maybe is better having a PIs instead for beach huntings...anyway...audio mod is interesting and seems could be good to avoid too transients on first power line...that could make bandido unstable for a while.
I've tested Carl's schematic in various conditions and find that it become unstable just only under 7.6volts at battery...under that voltage I've found that any sound it generates creates very huge response on amplifiers...thus making it unstable and unuseful in real searches. If you use an headphone and a new alkaline battery you don't see any unstability for at least 10-15 hours of working, that's very good for a handheld/portable unit.
What's really weak sometimes is sound...e.g. on speaker that is much lower than in other detectors (e.g. also whites) cause bandido is a power saving machine and don't waste much current on that.
A good, big speaker is required ...16ohm better. I'm using an old apple computer speaker in my unit and works OK.
Ivconic posted a zohori like audio-mod that could be used in bandido too...I think that good solution for audio ower could be AA or AAA batteries series....also NiMh-rechargable batteries or NiCd or the like - 4 elements...cause just another 9v (6f22) is not good if current is above 25mA in audio stage ...as often it is when you need to ear it in noisy environments out there.

Best regards,
Max

[Peter Morf]

Thanx for your quick reply Max.
You are probably right about the PI for beach hunting. I am working on a digital PI powered by a PIC but got stuck since I burned my ADC :/
Anyway.. two jumpers and the salt mode is off.

If I go with this PCB I'm going to try a 7.2V 1600mAH NiMh batterypack to drive sound, I have a lot of these, and an 8 ohms speaker from an old PC.

[oktoberfest1971]

bandido salt mode value

Hello Peter i saw your modification for Bandido and would like to try it in the German pcb project paul panzer 03 which are the correct values for R and C salt mode components?
May be i could not or i'm not able to see your complete post with components value...
Anyway to switch in this mode (salt mode) have to close both jumpers with an external switch is this ok? and i've to use shielded cable or normal cable to connect switch to PCB from my frontal control panel?
Sorry for my dummy question but i'm only at my second home made MD and don't want to waste time in stupid errors....
Ciao from Italy...

[Peter Morf]

values for salt mode components are not in the schematic. R = 22k, C = 3900p as Goodrat posted some time ago:
http://thunting.com/geotech/forums/s...ead.php?t=7244

For salt mode both jumpers should be set at 1-2, for normal operation: 2-3.
I use 2 jumpers without the switch, but I would try a normal cable first.
good luck =)

[Peter Morf]

I have completed this PCB (second one with 2 batteries) and found 2 errors on the board:

1. Connection between R6 and C43 is wrong, remove it.
2. IC 4024 pin 7 (GND) is connected to negative rail, remove it and connect to GND 0V.

Some problems... negative rail is only -1.9V. And when turning disc pot in "disc mode" nothing happens but in "retune" and "all metal" it reacts with sound. A bit odd to me

[Max]

I have completed this PCB (second one with 2 batteries) and found 2 errors on the board:

1. Connection between R6 and C43 is wrong, remove it.
2. IC 4024 pin 7 (GND) is connected to negative rail, remove it and connect to GND 0V.

Some problems... negative rail is only -1.9V. And when turning disc pot in "disc mode" nothing happens but in "retune" and "all metal" it reacts with sound. A bit odd to me

Hi Peter,
"Some problems... negative rail is only -1.9V. "

old problem... I know it very well! inefficient voltage converter you could rise up some voltage at -V using e.g. lower value resistances at base of complementary pair at, driven by 4024 at 5KHz...
Anyway real bandidoII can't give -5v at -V rail... but that's ok if you get something from -2.4 to say -3V (or few more). You have to use specified components or get lots of troubles... that stuff MC33178, TLC2262 etc work good with dual from +2.5/-2.5 volts (or find good replacements... low current supply, low noise, check old posts).
BTW -1.9V is not good!

"And when turning disc pot in "disc mode" nothing happens but in "retune" and "all metal" it reacts with sound. A bit odd to me"

Disc mode is motion-mode... you haven't any change in sound moving pots BUT just moving GEB knob... so seems normal you haven't any change, but if it works as it have to, you must get disc working... so ignoring e.g. foil.

My suggestions are:
- fix supply problem/ use right components if have too current drain
- set geb using ferrite core (find a point where it's ignored)
- use disc control and check if it's working or not

Also take care at possible other pcb mistakes.
I've used Gary's PCB (the large one, unsplitted) and checked it before assembling: everything OK and circuit works perfectly.

Best regards,
Max